Callyft, I think you nailed it on the head! A couple of google image searches matched what I have with "banded iron formation". Found a good description of the rock contents on one site: "alternating bands of red chert (jasper; cryptocrystalline quartz - SiO2), red hematite (iron oxide - Fe2O3), and silvery-gray specular hematite (iron oxide - Fe2O3)."
Thanks!